Wireless microphones of the type used in television productions, stage shows, lecture halls and churches operate on locally vacant TV channels. But, those channels are becoming scarce. Before the digital conversion, there were many vacant TV channels in local markets, leaving ample spectrum for wireless microphones.

The picture began to change in 2009, however, when the last full-power analog stations went off the air. Because digital TV stations can be packed more tightly than analog stations, the FCC was able to free up 18 channels for wireless use, which left fewer empty channels for wireless microphones.

A year ago, the FCC approved the first operation of “white space” devices that provide Wi-Fi-like service within some of the remaining vacant TV channels. The FCC reserved two channels in every market for wireless microphones, and provided for additional channels where needed. Nevertheless, a lot more devices will be trying to operate in a lot less spectrum. Then, last month, the FCC proposed “incentive auctions” designed to encourage broadcasters to give up still more channels.

Uses of wireless mics

Despite the squeeze on spectrum for wireless microphones, they are still indispensible in the entertainment industry. Even the FCC has acknowledged the irreplaceable nature of these devices. For decades, the agency issued licenses for TV-band wireless microphones to just a few categories of users: broadcasters and broadcast networks, cable TV operators, and movie and TV producers.

Other users, such as concert venues, college lecture halls, churches and even the FCC (in the context of its own meeting room) operated wireless microphones without authorization. But, these illegal operations, well known to the FCC, were well managed and caused virtually no interference to TV stations.